Search

Direct methane Solid Oxide Fuel Cells (SOFCs) operated under catalytic partial oxidation (CPOX) conditions are investigated, focusing on the processing of the anode support and the anode deactivation caused by carbon deposition. Anode-supported SOFCs based on gadolinium-doped ceria (GDC) electrolyte, and NiO-GDC anode support were fabricated by the gel-casting method. Suitable aqueous slurries formulations of NiO–GDC were prepared, starting NiO-GDC nanocomposite powders, agarose as gelling agent and rice starch as pore former. Electrochemical and mechanical tests evidenced that the support of 550 ± 50 µm thickness and 10 wt% pore former is a good candidate for direct-methane SOFCs. The cells operating under stoichiometric conditions of CPOX reached a performance of 0.64 W·cm−2 at 650 ºC, a very close value to that measured under humidified hydrogen (0.71 W·cm−2). The best electrochemical stability of the cell is achieved at a CH4/O2 ratio of 2.5, showing no evidence of carbon deposition and reducing nickel re-oxidation significantly.

[EN] The interest in hydrogen technologies has grown in recent years, mainly because an economy based on hydrogen can help to solve important challenges related to the global economy of the future: energy security and climate change. Taking advantage of this momentum, more and more countries are implementing a growing number of policies related to hydrogen. Indeed, the European Hydrogen Strategy establishes hydrogen as essential drivers for the total decarbonization of the current energy system in order to achieve the EU’s commitment related to carbon neutrality by 2050. However, the successful development of the hydrogen technologies requires the collaboration of the public and private sectors to accelerate its deployment and make more competitive its implementation at large-scale. The research groups that take part of the line of work dedicated to hydrogen technologies, within the CSIC Interdisciplinary Thematic Platform PTI Mobility 2030, work in this regard, developing their investigations in several important areas related to the hydrogen technologies such as hydrogen generation, storage, distribution and uses., [ES] El interés por las tecnologías del hidrógeno ha crecido en los últimos años, principalmente porque una economía basada en el hidrógeno puede dar respuesta a los grandes desafíos de la economía global del futuro: seguridad energética y cambio climático. Aprovechando este impulso, cada vez son más los países que están implementando un número creciente de políticas en favor del hidrógeno. Prueba de ello es la Estrategia Europea del Hidrógeno que establece al hidrógeno como un elemento esencial en la descarbonización total del actual sistema energético para alcanzar el compromiso de la UE con la neutralidad de carbono en 2050. No obstante, el desarrollo exitoso de las tecnologías del hidrógeno requiere que todos los actores, incluidos los sectores público y privado, aumenten sus esfuerzos para acelerar su despliegue y hacer que su implantación a gran escala resulte competitiva. Los grupos de investigación que forman parte del área de trabajo de tecnologías del hidrógeno, dentro de la Plataforma Temática Interdisciplinar PTI Mobility 2030 del CSIC, trabajan en este sentido, desarrollando su labor en áreas tan diversas como la generación, el almacenamiento, la distribución y los usos del hidrógeno.

Nickel–yttria stabilized zirconia (Ni–YSZ) cermet is the most commonly used anode in solid oxide fuel cells (SOFCs). The current article provides an insight into parameters which affect cell performance and stability by reviewing and discussing the related publications in this field. Understanding the parameters which affect the microstructure of Ni–YSZ such as grain size (Leng et al 2003 J. Power Sources 117 26–34) and ratio of Ni to YSZ, volume fraction of porosity, pore size and its distribution, tortuosity factor, characteristic pathway diameter and density of triple phase boundaries is the key to designing a fuel cell which shows high electrochemical performance. Lack of stability has been the main barrier to commercialization of SOFC technology. Parameters influencing the degradation of Ni–YSZ supported SOFCs such as Ni migration inside the anode during prolonged operation are discussed. The longest Ni-supported SOFC tests reported so far are examined and the crucial role of chromium poisoning due to interconnects, stack design and operating conditions in degradation of SOFCs is highlighted. The importance of calcination and milling of YSZ to development of porous structures suitable for Ni infiltration is explained and several methods to improve the electrochemical performance and stability of Ni–YSZ anode supported SOFCs are suggested.

Nanomaterials have attracted much attention over the last decades due to their very different properties compared to those of bulk equivalents, such as a large surface-to-volume ratio, the size-dependent optical, physical, and magnetic properties. A number of solution fabrication methods have been developed for the synthesis of metal and metal oxides nanoparticles, but few solid-state methods have been reported. The application of nanostructured materials to electronic solid-state devices or to high-temperature technology requires, however, adequate solid-state methods for obtaining nanostructured materials. In this review, we discuss some of the main current methods of obtaining nanomaterials in solid state, and also we summarize the obtaining of nanomaterials using a new general method in solid state. This new solid-state method to prepare metals and metallic oxides nanostructures start with the preparation of the macromolecular complexes chitosan·Xn and PS-co-4-PVP·MXn as precursors (X = anion accompanying the cationic metal, n = is the subscript, which indicates the number of anions in the formula of the metal salt and PS-co-4-PVP = poly(styrene-co-4-vinylpyridine)). Then, the solid-state pyrolysis under air and at 800 °C affords nanoparticles of M°, MxOy depending on the nature of the metal. Metallic nanoparticles are obtained for noble metals such as Au, while the respective metal oxide is obtained for transition, representative, and lanthanide metals. Size and morphology depend on the nature of the polymer as well as on the spacing of the metals within the polymeric chain. Noticeably in the case of TiO2, anatase or rutile phases can be tuned by the nature of the Ti salts coordinated in the macromolecular polymer. A mechanism for the formation of nanoparticles is outlined on the basis of TG/DSC data. Some applications such as photocatalytic degradation of methylene by different metal oxides obtained by the presented solid-state method are also described. A bri

[EN] The laser is a powerful tool for materials processing, incorporated already in many industrial processes and laboratory procedures. In this work, we are concerned with laser processing applied to research and development of ceramics for electrochemical cells and other high temperature oxide ceramics for energy applications. Solidification of single crystals or composites of relevant oxides can be performed by the laser assisted floating zone method, providing samples for structural, mechanical or functional fundamental research, as well as knowledge about its manufacture by melt processes. Selective laser melting of these ceramic oxides is a very promising technology, at the research level. Successful examples of surface laser melting of oxide eutectic composites are presented. The technologies of subtractive laser processing of ceramics (cutting, drilling, structuring, cleaning, etc.) are more developed, and the research is directed towards the optimization of mechanisms, increase of resolution and efficiency and the investigation of the effects of the laser treatment on the functional performance. Different laser processes of SOC (solid oxide cell) components are shown to decrease the ohmic, concentration and activation losses. The manuscript describes the state-of-the art of the technologies as applied to oxide and composite materials present in solid oxide electrochemical devices (SOFC, SOEC, and batteries) and selective emitters for thermophotovoltaics, with emphasis on the last achievements by the authors team., [ES] El láser es una potente herramienta para el procesamiento de materiales, incorporada ya en muchos procesos industriales y procedimientos de laboratorio. En este trabajo nos ocupamos del procesamiento láser aplicado a la investigación y desarrollo de cerámicas para celdas electroquímicas y otras cerámicas de óxido de alta temperatura para aplicaciones energéticas. La solidificación de monocristales o composites de óxidos relevantes se puede realizar mediante el método de zona flotante asistida por láser, proporcionando muestras para investigación básica estructural, de propiedades mecánicas o funcionales, así como conocimiento sobre su fabricación mediante procesos de fusión. La fusión selectiva por láser de estos óxidos cerámicos es una tecnología muy prometedora, cuyo desarrollo es todavía incipiente. Se presentan ejemplos exitosos de fusión por láser de superficie de compuestos eutécticos de óxidos. Las tecnologías sustractivas de procesamiento de cerámicas con láser (corte, taladrado, estructuración, limpieza, etc.) están más desarrolladas, y la investigación se dirige hacia la optimización de procedimientos, aumento de resolución y eficiencia y la investigación de los efectos del tratamiento láser sobre el rendimiento funcional. Diferentes procesos láser de los componentes de celda de óxido sólido disminuyen las pérdidas óhmicas, de concentración y de activación. El manuscrito describe el estado actual de las tecnologías aplicadas a óxidos y materiales compuestos presentes en dispositivos electroquímicos de óxidos sólidos (SOFC, SOEC y baterías) y emisores selectivos para aplicaciones termofotovoltaicas, con énfasis en los últimos logros del equipo.

An efficient way for boosting the performance of solid oxide electrodes is the infiltration of metallic nanoparticles into both electrodes. In this work we will focus on improving the performance of standard lanthanum strontium manganite oxygen electrodes, by the addition of different metal oxide nanoparticles. First studies will be performed using cerium oxide nanoparticles, as this is the classic oxide already proposed in the literature. Other novel metal oxides such as praseodymium or manganese oxide will be explored, as studies in the literature for these two metal oxides are very scarce. The effect of metal oxide infiltration into LSM/YSZ oxygen electrodes will be studied in both symmetrical cells and complete microtubular cells using conventional fuel electrodes (NiO-YSZ) and electrolytes (YSZ). The obtained current densities in both fuel cell and electrolysis modes are significantly enhanced in comparison with other results in the literature for microtubular configuration.

The authors regret that in the above article, affiliation c is mistaken. Therefore, afiliation c should be: c Departamento de Química de los materiales, Laboratorio de electroquímica Medio ambiental, LEQMA, Universidad de Santiago de Chile, Avenida Libertador Bernardo O'Higgins 3363, Estación Central, Santiago 9170376, Chile The authors would like to apologize for any inconvenience caused.

This paper is devoted to the study of the electrical conductivity of tantalum-doped zirconia ceramics prepared by spark plasma sintering. In this study, the temperature dependence of conductivity in as-prepared specimens and in those previously annealed in air is determined and compared. A semi-empirical model, which is based on the oxidation states of the cations, has been developed and successfully assessed. According to this, the conductivity is basically controlled by the diffusion of tetravalent zirconium cations in both cases, although the concentration of these species varies drastically with the amount of induced oxygen vacancies. This is a quite unexpected fact, since conductivity is normally controlled by anionic diffusion in zirconia ceramics. This option is forbidden here due to the presence of substitutional pentavalent cations. Therefore, conductivity values are much lower than those reported in trivalent or divalent substitutional cation doped zirconia ceramics.

Thoria was prepared using a solid-state method from the macromolecular precursor Chitosan·Th(NO3)4 (chitosan) and PS-co-4-PVP·Th(NO3)4 (PVP). The morphology and the average size of ThO2 depend of the chitosan and PS-co-4-PVP polymer forming the precursor. Their photoluminescent properties were investigated, finding a dependence of their intensity emission maxima, with the nature of the precursor polymer. The photocatalytic activity of ThO2 toward the degradation of methylene blue was measured for the first time, finding a degradation of about 66% in 300 min. The inclusion of ThO2 into SiO2 and TiO2 was achieved by the solid-state pyrolysis of the macromolecular composites Chitosan·Th(NO3)4//MO2 and PS-co-4-PVP·Th(NO3)4//MO2, MO2 = SiO2 or TiO2. The ThO2 exhibits a homogeneous dispersion inside the silica, showing sizes of about 40 and 50 nm for the chitosan and PVP polymer precursors, respectively. The luminescent properties of the ThO2/SiO2 and ThO2/TiO2 composites were also studied, finding a decrease in intensity when introducing the SiO2 or TiO2 matrices. The photocatalytic behavior to methylene blue degradation of ThO2 and their composites ThO2/SiO2 and ThO2/TiO2 was investigated for the first time, with them in the following order: ThO2 > ThO2/TiO2 > ThO2/SiO2.

The insight into the mechanism of the unprecedented formation of pure anatase TiO2 from the macromolecular (Chitosan)•(TiOSO4)n precursor has been investigated using micro Raman spectroscopy, Scanning Electron Microscopy (SEM) and thermogravimetric/differential thermal analysis (TGA/DTA). The formation of a graphitic film was observed upon annealing of the macromolecular precursor, reaching a maximum at about 500 °C due to decomposition of the polymeric chain of the Chitosan and (PS-co-4-PVP) polymers. The proposed mechanism is the nucleation and growth of TiO2 nanoparticles over this graphitic substrate. SEM and Raman measurements confirm the formation of TiO2 anatase around 400 °C. The observation of an exothermic peak around 260 °C in the TGA/DTA measurements confirms the decomposition of carbon chains to form graphite. Another exothermic peak around 560 °C corresponds to the loss of additional carbonaceous residues.

A solid-state phase control of TiO2 by the use of different macromolecular complex precursors is reported for the first time. During the formation of TiO2 nanoparticles, chitosan and poly(styrene-co-4-vinylpyridine) polymers can act as solid-state template producing areas after carbonization, where the TiO2 nucleates. It seems that the location of metal centers through the polymeric chain (i.e., the distance between the metal centers) strongly influences the morphology and particle size of the photocatalyst. To demonstrate the application value of our different TiO2 structures, the photocatalytic behavior was explored. The efficient photocatalytic decoloration of methylene blue on different polymorphic forms of nanostructured TiO2 is confirmed. The best photocatalyst achieved a 98% discoloration rate in only 25 min when the pH of the solution was 9.5, improving the efficiency of the standard photocatalyst Degussa P25 without the addition of other phases or dopants. The novelty of the present work is that, by means of an appropriate synthesis, the three main factors (morphology, size, and crystalline phase) that allow modulating the photocatalytic response of titania material can be tuned simultaneously. This control has allowed an advance in the properties of the material, managing to increase the photoresponse in a short time.

Three amphiphilic carbon nanotube-supported Ni catalysts have been prepared and tested regarding their emulsifying properties for the hydrogenation of furfural. The solid catalysts and emulsions were systematically characterized by different high-resolution techniques. The catalytic hydrogenation of furfural was evaluated in a mixture of two immiscible solvents under mild conditions. The wettability of the catalysts was tuned by adjusting the severity of the acid treatments during the catalyst’s synthesis. It was found that the catalysts wettability played a crucial role in enhancing the catalytic activity. The lowest furfural conversion observed over Ni/CNTox2 and Ni/CNTp were attributed to the missing possibility to form stable emulsion droplets due to their either extreme hydrophilic or hydrophobic character, respectively. In contrast, the highest catalytic activity verified for Ni/CNTox1 catalyst was traced back to an improved dispersion of the nickel nanoparticles as well as the possible formation of stable emulsion droplets due to its amphiphilic character. All catalysts were selective towards cyclopentanone. However, the highest yield of cyclopentanone was found over the Ni/CNTox1 catalyst, which migrated towards the organic phase after its formation. This result highlights the simultaneous reaction and separation of key reaction products in emulsion, which greatly simplifies the isolation stages of target products.

The conductivity of ceramic ionic materials is highly influenced by dopant segregation at the grain boundaries or interfaces, which usually induces a depletion of charge carriers by space charge effects. Hence, obtaining interfacial configurations that promote the formation of oxygen vacancies is highly desirable. In this paper we have combined high resolution electron microscopy (HREM), kelvin probe force microscopy (KPFM) and density functional theory (DFT) to elucidate the equilibrium state of CGO–CoO and CGO–NiO eutectic ceramics (CGO: cerium-gadolinium oxide). HREM proves that the interface is sharp, formed by a single common oxygen plane, and that in CGO–CoO the concentration of gadolinium ions at the interface is almost three times greater than in the bulk, while they distribute homogeneously in the CGO–NiO system. Accordingly, KPFM experiments suggest that interfacial ionic conductivity is much higher in CoO–CGO than in NiO–CGO. DFT demonstrates that Gd segregation in the CGO–CoO reduces the interface energy, contributing to its stability. The Gd-oxygen vacancy complexes compensate the interfacial ionic charge density discontinuity. Additionally, the induced local distortions around the defect release the strain associated with the lattice mismatch. Therefore, we show that in CGO-based eutectics the structure and ionicity of the constituent oxides are essential to promote the interface dopant segregation, indicating a new way to produce nanocomposites with enhanced interfacial ionic conductivity.

The simple reaction of chitosan with metallic salts yields (chitosan) (MLn)x, MLn = MnCl2, CoCl2, NiCl2, macromolecular complexes which, after a thermal treatment at 800 °C under air, give nanostructured Mn2O3, Co3O4 and NiO. The polymer acts as a template in the solid state, which is eliminated after the combustion process. At an intermediate stage, a layered graphitic carbon matrix was observed by HRTEM over the grown metal oxides. A mechanism for the growth of nanostructured oxides is discussed, including Raman studies. The nanostructured Mn2O3, Co3O4 and NiO particles grow over graphite layers and the solid-state role of chitosan is crucial for the formation of this graphite substrate. An antiferromagnetic transition was observed in Co3O4 nanoparticles, with TN = 38 K, whereas NiO nanoparticles behave as a superparamagnetic material with a blocking temperature above 300 K.

The interfacial area between the electrode and the electrolyte of solid oxide fuel cells (SOFCs) is increased by a pulsed-laser machining to expand the active electrochemical reaction region. The pulsed-laser machining is performed on the surface of the YSZ flat electrolytes to fabricate micro-patterned craters. The surface profiles of the patterned electrolytes are measured by a 3D laser profiler. Then, LSM cathode is fabricated on the laser-machined surface of the YSZ electrolyte, while Ni-YSZ anode on the flat side. The performance of the fabricated cell with the patterned interface is experimentally evaluated at 900°C and compared with that of the conventional cell having the flat interface. 3D numerical simulations are also performed on the patterned cell to understand the distributions of the activation overpotentials and the charge-transfer current at the interface. A power density enhancement is confirmed in the cell with the patterned interface in both experiment and simulation.

Incorporation of Au° inside SiO2 was achieved by a solid-state method from the pyrolysis of the composites (Chitosan)•(AuCl3)n•(SiO2)m and (PS-co-4-PVP)•(AuCl3)n•(SiO2)m Similarly, the incorporation of Ag° inside SiO2 it was made from thermal treatment of the composites (Chitosan)•(AgNO3)n•(SiO2)m and (PS-co-4-PVP)•(AgNO3)n•(SiO2)m. The nature of the polymer controls the particle size for the Au/SiO2 composite, while that for the Ag/SiO2 both, polymer Chitosan and PS-co-4-PVP, produces similar particle size. In the case of the composite Ag/SiO2 the particle size as small as 5 nm were obtained.The 1:1 or 1:5 metal/polymer ratios, as well as the nature of the polymer in the macromolecular precursors (Chitosan)•(AuCl3)n•(SiO2)m and (PS-co-4-PVP)•(AuCl3)n•(SiO2)m influences the dispersion of the Au° nanostructures inside SiO2 matrix. The results are compared with those previously obtained for bimetallic composites Au/Ag//SiO2. A formation mechanism of the Au°/SiO2 and Ag°/SiO2 composites involving the combustion of the organic matter and the growth of the Au° and Ag° nanoparticles inside the holes, generated from the combustion process, is proposed.

In an effort to discover new inorganic UV absorbers, titania included into silica was prepared using a solvent-less solid state method involving the pyrolysis of the as prepared precursor Chitosan·(TiOSO4)/SiO2, as an alternative and versatile way to using these compounds for practical applications. The new TiO2/SiO2 composite was characterized by PXRD, SEM–EDS, TEM and UV–Vis absorption analysis. The SEM–EDS mapping images show a uniform distribution of TiO2 into the silica matrix. The optical properties of the composite have shown an interesting result related to high absorption of UVB rays and an improved absorption of UVA rays than pure TiO2. Efficient suppression of photocatalytic behavior of TiO2, when is incorporated into silica, was evidenced from 85 to 31%, suggesting it material as alternative inorganic UV absorber to remains the properties of the methylene blue dye. These results reveal their potential use in practical textile industry and UV protection agent to avoid human damage.

This work is concentrated on getting a reply to the following question: how does the grain size of boron carbide specimens influence on their mechanical and electrical response? It is a common issue that both essential properties are usually affected by the grain boundaries. To this purpose, a set of near fully-dense boron carbide specimens were prepared by spark plasma sintering. In order to reduce residual porosity and grain-size effects, nanoindentation tests at room temperature were conducted. DC conductivity was measured through four-point test technique from room temperature up to 800 °C. The results show that hardness can reach values as high as ∼60 GPa and plasticity onset takes place at around 23 GPa by dislocation nucleation. Regarding the conductivity, it is found that grain boundaries can block the mobility of bipolarons in an effective way. A simple additive law is provided to account for the resistivity of boron carbide polycrystals.

A controlled physical method without any solvent was used to grow Ag nanoparticles on TiO2 by use of mercaptoacetic acid as a bifunctional surface modifier. The fabricated Ag-TiO2 tight heterojunction was proposed as an innovative photocatalytic material. The particle size, chemical nature, morphology, and chemical bonding between mercaptoacetic acid, Ag, and TiO2 were characterized by UV–vis absorption spectroscopy, powder X-ray diffraction, Raman spectroscopy, transmission electron microscopy, and scanning electron microscopy. The photocatalytic activity of TiO2 combined with the excellent electron acceptor abilities and visible light absorption of small spherical Ag nanoparticles resulted in efficient photoinduced degradation of a cationic organic pollutant (methylene blue) under UV–vis light. The nanocatalyst material obtained with a sputter time of 30 s under simulated sunlight results in almost complete degradation (97%) of methylene blue after 120 min. The particle size, tight attachment to TiO2, and distribution of Ag nanoparticles were controlled for the first time through a physical method by use of controlled chemical bonding to bifunctional surface modifiers and an appropriate sputter deposition time.

Although economically competitive SOFC systems seems to be ready for commercialization, a broad inventory of key starting materials and fabrication processes are needed to enhance systems and reduce costs. These necessities are raised by the demands for large scale SOFC industrial production. Taking into account these reasons, we have synthesized the mean components of a fuel cell, on a large scale, by the glycine nitrate combustion method. The synthesized different components of SOFC have been the interconnector protective coating (MnCo1.9Fe0.1O4), contact layer (LaNi0.6Fe0.4O3), cathode (La0.6Sr0.4FeO3), interlayer (Sm0.2Ce0.8O1.9), electrolyte (ZrO2)0.92(Y2O3)0.08 and anode (Ni0.3O-(ZrO2)0.92(Y2O3)0.08) material, obtaining reproducible pure samples and amounts up to 12 g for each batch, being able to increase easily this amount to lots of hundred of grams. The obtained materials have been characterized by inductively coupled plasma atomic emission spectroscopy (ICP-AES) and X-ray fluorescence (XRF), X-ray diffraction (XRD), dilatometry, scanning electron microscopy (SEM), particle size distribution and conductivity measurements.

Bimetallic Au/Ag nanostructures have been included inside SiO2 by pyrolysis of the macromolecular complexes Chitosan·(MLn/M′Ln)n·SiO2 and PSP-4-PVP·(MLn/M′Ln)n·SiO2 with MLn = AuCl3 and M′Ln = Ag(CF3SO3). The structural characterization was performed by XRD (X-ray diffraction of powder) and UV–Vis, and the microstructural characterization was done by SEM/EDS analysis HRTEM. The resulting products from the pyrolytic precursors PSP-4-PVP·(AuCl3/AgSO3CF3)n·SiO2 1:1 (1), PSP-4-PVP·(AuCl3/AgSO3CF3)n·SiO2 1:5 (2), Chitosan·(AuCl3/AgSO3CF3)n·SiO2 1:1 (3) and Chitosan·(AuCl3/AgSO3CF3)n·SiO2 1:5 (4) were Au/Ag//SiO2, Au//SiO2 and Ag//SiO2 as well as isolated Au and Ag, depending on the polymeric precursor. The Chitosan polymer precursor induces mainly Ag and Ag/SiO2 nanostructures, while PSP-4-PVP induces mainly Au/Ag//SiO2 nanostructures. This can be explained by the facility to link Ag+ to the NH2 and OH groups of Chitosan than to the pyridine of PSP-4-PVP. On the contrary, Au3+ exhibits most coordination ability to pyridine groups of PSP-4-PVP than NH2- and OH-groups of Chitosan. EDS mapping analysis indicates a uniform distribution of the Au/Ag nanostructure inside the SiO2 matrix. Using reflectance diffuse analysis, the plasmon is consistent with the Au/Ag alloys structure.

Una SOFC (Solid Oxide Fuel Cell) o pila de combustible de óxido sólido, es el tipo de pila de hidrógeno más eficiente actualmente. Normalmente, su temperatura de trabajo se encuentra entre los 600 ºC y 1000 ºC, lo cual conlleva un problema de estabilidad termoquímica de los componentes y sus interfases, que acaba derivando en una disminución de la efectividad y duración de la celda. Una posible solución que se está estudiando en el ICMA, en el grupo de Procesado y Caracterización de Cerámicas Estructurales y Funcionales (grupo de investigación dentro del cual se va a realizar este proyecto), es sustituir el material del electrolito que se utiliza actualmente, la YSZ (circona estabilizada con itria), por nuevos materiales de tipo oxiapatita, los cuales presentan mejores valores de conducción de los iones de oxígeno a temperaturas intermedias, lo que permitiría bajar el punto de operación del sistema al rango de los 700 - 800ºC. Sin embargo, estos materiales presentan importantes limitaciones en su procesado, debido fundamentalmente a su difícil densificación, lo que hace necesario un estudio minucioso de su proceso de sinterización. En este proyecto se estudiarán dos oxiapatitas en concreto: La9.67Si6O26.5 y La9.67Si3Ge3O26.5 El objetivo principal de este proyecto es fabricar una pila microtubular soportada sobre ánodo con este nuevo tipo de material. Para ello habrá que: 1. Sintetizar las oxiapatitas, realizando las mezclas, moliendas y tratamientos térmicos adecuados, comprobando después su cristalinidad mediante difracción de rayos X y espectroscopia Raman así como sus propiedades de conducción iónica mediante espescroscopia de impedancias (EIS). 2. Caracterizar y optimizar la morfología del polvo de los compuestos obtenidos para su posterior utilización en la fabricación de las pilas. Para ello, se estudiará la distribución del tamaño de partícula, se realizarán ensayos de dilatometría para determinar las temperaturas de sinterización del electrolito y por último